Celestia Forums

I was viewing the "tour of venus" script and in the end i remember that it said that the planet is a "good example of a runaway greenhouse effect" - this means that our planet can became like venus? By polluting the atmosphere only?

If this can happen ( and i suppose that if scientists say that it can happen ... then it can ), then how Venus got this atmosphere in the first place? Was venus a green planet like earth that became like that sometime in the past? how?

Dunno about 'green', but it was a lot more like Earth in the past, with oceans on its surface. The sun was dimmer in the distant past so the environment could stay stable... but over time the sun got hotter and the cytherean environment couldn't balance that. The general idea is that the oceans evaporated, CO2 trapped in the water escaped into the atmosphere, and between the steam and CO2 a massive greenhouse effect ensued and literally roasted the planet. We think this is the case because the deuterium:hydrogen ratio in the atmosphere is very high, which is indicative that there were large amounts of water on the surface once.

This will possibly happen to Earth one day (I think current estimates are that the sun will become too warm for our environment to counteract in a couple of hundred million years). Our current pollution won't cause this to happen though, but it will definitely cause major climate changes and a rise in sea levels, and that's bad enough considering how many people live in coastal regions.

The estimate I've heard for Earth is 500 million years, and the Earth will be too warm to support life in its current form.

Better make your tickets to Mars now.......

d.m.f.